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Fri, 19 Jun 2026 05:58:03 -0700 (PDT) Date: Fri, 19 Jun 2026 14:58:01 +0200 From: Petr Mladek To: Breno Leitao Cc: Tejun Heo , Lai Jiangshan , Song Liu , linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH RFC 1/3] workqueue: only show running workers in stall diagnostics Message-ID: References: <20260616-wq_dump_petr-v1-0-b57473ca6d18@debian.org> <20260616-wq_dump_petr-v1-1-b57473ca6d18@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260616-wq_dump_petr-v1-1-b57473ca6d18@debian.org> On Tue 2026-06-16 09:44:39, Breno Leitao wrote: > show_cpu_pool_busy_workers() dumps every in-flight worker in the pool's > busy_hash, including workers that are not currently running on the CPU. > Restore the task_is_running() filter so only running workers are dumped. > > When no running worker is found the pool may be stuck, unable to wake an > idle worker to process pending work, and the watchdog would otherwise > give no feedback. Add show_pool_no_running_worker() to report the pool > id, CPU, idle state, and worker counts in that case. > > The pool info message is printed inside pool->lock using > printk_deferred_enter/exit, the same pattern used by the existing > busy-worker loop, to avoid deadlocks with console drivers that queue > work while holding locks also taken in their write paths. > > This has been running on the Meta fleet for a while and caught some real > issues, for instance EFI stalls stalling the workqueue [1]. > > Link: https://lore.kernel.org/all/20260616-efi_timeout-v3-0-76dd1d26657b@debian.org/ [1] > Suggested-by: Petr Mladek > Signed-off-by: Breno Leitao > Fixes: 8823eaef45da7 ("workqueue: Show all busy workers in stall diagnostics") It looks good to me. And it is good to know that it helped in the real life. Reviewed-by: Petr Mladek Best Regards, Petr